稀土纳米系统的相干特性及其在量子技术中的应用研究

量子信息技术作为国家战略科技力量之一，是当今国际世界普遍重视和高度竞争的焦点领域。要解决量子信号的产生、处理、传输、同步和存储等一系列问题，对量子材料的性能提出了非常严格的要求。稀土离子（Rare earth ions, RE³⁺）掺杂晶体材料由于具有稳定的固态物性和出色的光学性质，在量子信息存储、量子频率转换、确定性量子单光子源以及量子调控等方向有着巨大的应用前景。为了满足未来高度集成的混合量子系统和微型化量子设备的苛刻要求，开发高性能RE³⁺纳米晶体材料，并在其基础上进行量子态的精密探测与操控，已成为当前RE³⁺量子晶体研发的前沿和热点问题。

本论文以Eu³⁺:Y₂O₃纳米量子晶体为研究对象，致力于其湿化学法制备、相干特性及其在量子技术中的应用研究。采用自下而上的均相沉淀化学合成路线，通过优化制备工艺，即调节沉淀剂碳酰胺（尿素，CO(NH₂)₂）的浓度、反应容器、沉淀反应时长、反应温度等参数，制备出不同粒径系列的Eu³⁺:Y(OH)CO₃·3/2H₂O（Eu³⁺:YOC）碳酸盐沉淀前驱体。随后，采用高温煅烧工艺使该前驱体氧化分解，获得相应的系列Eu³⁺:Y₂O₃纳米粉体。通过优化高温煅烧等后处理机制，即后处理的气氛、时间、温度、次数和升降温速率等参数，研究了Eu³⁺:Y₂O₃纳米粉体的粒径、初始晶粒尺寸、氧缺陷、分散性和均匀性等性能受制备参数的影响规律，为进一步获得高结晶质量的单分散Eu³⁺:Y₂O₃纳米粉体提供依据。

在Eu³⁺:Y₂O₃纳米粉体的量子相干性能研究方面，设计并完善了纳米粉体的样品架构造，搭建了合适的实验光路和实验设备，解决了强散射Eu³⁺:Y₂O₃纳米粉体在极低温稀释制冷机中的微弱光学探测问题。通过对制备的系列Eu³⁺:Y₂O₃纳米粉体进行非均匀线宽和荧光寿命表征测试，分析了Eu³⁺:Y₂O₃的制备工艺-微观结构-相干性能之间的构效关系。

As one of the national strategic scientific and technological forces, quantum information technology is the focus of international attention and highly competitive field. In order to solve a series of problems of quantum signal generation, processing, transmission, synchronization and storage, the performance of quantum materials is very strict requirements. Rare Earth ions (RE³⁺) doped crystal materials have great application prospects in quantum information storage, quantum frequency conversion, deterministic quantum single photon source and quantum control due to their stable solid properties and excellent optical properties. In order to meet the demanding requirements of highly integrated hybrid quantum systems and miniaturized quantum devices in the future, the development of high-performance RE³⁺ nanocrystal materials and the precise detection and manipulation of quantum states based on them have become the forefront and attractive issues in the research and development of rare earth nano-systems.

In this thesis, Eu³⁺:Y₂O₃ nano quantum crystal is taken as the research object, and its wet-chemical preparation, coherence properties and applications in quantum technology are studied. Using bottom-up homogeneous precipitation chemical synthesis route, by optimizing the preparation process, that is, adjusting the concentration of precipitant carbamide (urea, CO(NH₂)₂), reaction vessel, precipitation reaction time, reaction temperature and other parameters, A series of Eu³⁺:Y(OH)CO₃·3/2H₂O (Eu³⁺:YOC) carbonate precipitation precursors with different particle sizes were prepared. Subsequently, the precursor was oxidized and decomposed by high temperature calcination process to obtain the corresponding series of Eu³⁺:Y₂O₃ nano-powders. By optimizing the post-treatment mechanism of high-temperature calcination, namely, the parameters of post-treatment such as atmosphere, time, temperature, times and temperature rise and drop rate, the influence of preparation parameters on the particle size, initial grain size, oxygen defect, dispersity and uniformity of Eu³⁺:Y₂O₃ nano-powder was studied. It provides a basis for further obtaining monodisperse Eu³⁺:Y₂O₃ nano-powder with high crystallization quality.

In the study of the quantum coherence properties of Eu³⁺:Y₂O₃ nano-powder, the sample frame structure of nano-powder was designed and improved, and the appropriate experimental optical path and equipment were set up, which solved the weak optical detection problem of strongly scattered Eu³⁺:Y₂O₃ nano-powder in the ultra-low temperature dilution refrigerator. A series of Eu³⁺:Y₂O₃ nano-powders were prepared by non-uniform linear width and fluorescence lifetime characterization tests, and the structure-activity relationship between the preparation process, microstructure and coherence properties of Eu³⁺:Y₂O₃ nano-powders was analyzed.

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